Problem: If you flip three fair coins, what is the probability that you'll get at least two heads?
Explanation: $\text{Probability} = \dfrac{\text{Favorable outcomes}}{\text{Total possible outcomes}}$ If we flip three coins, there are $2$ possible outcomes for each individual flip, so there are $2\times2\times2=8$ total possible outcomes. Each outcome is equally likely. The green rows show the outcomes with at least two heads. There are $4$ favorable outcomes. First Second Third ${\text{H}}$ ${\text{H}}$ ${\text{H}}$ ${\text{H}}$ ${\text{H}}$ ${\text{T}}$ ${\text{H}}$ ${\text{T}}$ ${\text{H}}$ H T T ${\text{T}}$ ${\text{H}}$ ${\text{H}}$ T H T T T H T T T The probability of getting at least two heads is $4$ out of $8$, or $\dfrac48$. We can simplify this fraction to $\dfrac12$.